Field
The present application relates generally to light emitting diodes, and more particularly, to surface-textured encapsulations for use with light emitting diodes to provide for enhanced light output.
Background
Light emitting diodes (LEDs) for use as indicators are well known. LEDs have been used extensively for this purpose in consumer electronics. For example, red LEDs are commonly used to indicate that power has been applied to devices such as radios, televisions, video recorder (VCRs) and the like.
Recently, high-power LEDs have seen increased use in general lighting applications. For example, power LEDs can now be found in overhead lighting, table lamps, and in automotive application, such as in automobile headlamps. Typically, high-power LEDs are provided as part of an assembly comprising a LED mounted to a substrate and protected by encapsulation. Light emitted from the LED passes through the encapsulation before it is visible to a user. However, there is light loss in the encapsulation layer in the LEDs. This is due in part to internal reflections occurring at the interface between the encapsulation and the air.
Various techniques have been tried to improve the light output of the LEDs. For example, the addition of a lens to the encapsulation layer has been used to extract additional light. However, the additional lens material impacts the thermal properties of the LED assembly by reducing heat dissipation. Also, the addition of the lens increases the cost of processing and manufacture of the LED assembly.
Therefore, what is needed is a way to increase the optical output of high power LEDs while providing excellent heat dissipation and reduced processing and manufacturing costs.